IRAC Near-Infrared Features in the Outer Parts of S4G Galaxies
Seppo Laine, Johan H. Knapen, Juan-Carlos Munoz-Mateos, Taehyun Kim, Sebastien Comeron, Marie Martig, Benne W. Holwerda, E. Athanassoula, Albert Bosma, Peter H.… 展开作者
Seppo Laine, Johan H. Knapen, Juan-Carlos Munoz-Mateos, Taehyun Kim, Sebastien Comeron, Marie Martig, Benne W. Holwerda, E. Athanassoula, Albert Bosma, Peter H. Johansson, Santiago Erroz-Ferrer, Dimitri A. Gadotti, Armando Gil de Paz, Joannah Hinz, Jarkko Laine, Eija Laurikainen, Karin Menendez-Delmestre, Trisha Mizusawa, Michael W. Regan, Heikki Salo, Kartik Sheth, Mark Seibert, Ronald J. Buta, Mauricio Cisternas, Bruce G. Elmegreen, Debra M. Elmegreen, Luis C. Ho, Barry F. Madore, Dennis Zaritsky
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26 pages, 16 embedded + 100 online-only figures, accepted for publication in MNRAS
We present a catalogue and images of visually detected features, such as asymmetries, extensions, warps, shells, tidal tails, polar rings, and obvious signs of mergers or interactions, in the faint outer regions (at and outside of R_25) of nearby galaxies. This catalogue can be used in future quantitative studies that examine galaxy evolution due to internal and external factors. We are able to reliably detect outer region features down to a brightness level of 0.03 MJy/sr per pixel at 3.6 microns in the Spitzer Survey of Stellar Structure in Galaxies (S4G). We also tabulate companion galaxies. We find asymmetries in the outer isophotes in 22+/-1 per cent of the sample. The asymmetry fraction does not correlate with galaxy classification as an interacting galaxy or merger remnant, or with the presence of companions. We also compare the detected features to similar features in galaxies taken from cosmological zoom re-simulations. The simulated images have a higher fraction (33 per cent) of outer disc asymmetries, which may be due to selection effects and an uncertain star formation threshold in the models. The asymmetries may have either an internal (e.g., lopsidedness due to dark halo asymmetry) or external origin.
Using Spitzer/IRAC observations of a region to be observed by the CoRoT satellite, we have unraveled a new complex star-forming region at low metallicity in the outer Galaxy. We perform a study of S284 in order to outline the chain of events in this star-forming region. We used four-band Spitzer/IRAC photometry as well as Halpha imaging obtained with INT/WFC. Combining these data with the optical photometry obtained in the frame of CoRoTs preparation and the 2MASS catalog we analysed the properties and distribution of young stellar objects (YSOs) associated with point-like sources. We also stu…
We present the {\it Spitzer}-IRAC images of the S235 star forming complex that includes the East~1 & 2, Central and S235 A & B regions. In addition, we present the near-infrared images of the S235 A & B regions. The IRAC photometry reveals on-going star formation, with 86 Class 0/I and 144 Class II YSOs in the entire S235 complex. Nearly 73% of these YSOs are present in clusters with a maximum surface density of 120 YSOs/pc$^{2}$ (in the vicinity of S235A & B regions). A few YSOs, possibly in an arc-like formation, are identified towards the south of S235A region, which may be speculated as an…
We present the first results from an extended survey of the Andromeda galaxy (M31) using 41.1 h of observations by Spitzer-IRAC at 3.6 and 4.5$\,μ$m. This survey extends previous observations to the outer disc and halo, covering total lengths of 4$.\!\!^\circ$4 and 6$.\!\!^\circ$6 along the minor and major axes, respectively. We have produced surface brightness profiles by combining the integrated light from background-corrected maps with stellar counts from a new catalogue of point sources. Using auxiliary catalogues we have carried out a statistical analysis in colour-magnitude space to disc…
Star-forming regions are often associated with nebulosity. In this study, we investigated infrared diffuse emission in Spitzer IRAC images. The infrared nebula L1527 traces outflows emanating from a low-mass protostar. The nebular color is consistent with the color of a stellar photosphere with large extinction. Nebulae around the HII region W5-East are bright in the infrared. These colors are consistent with the model color of dust containing polycyclic aromatic hydrocarbon (PAH). The strength of ultraviolet irradiation of the nebulae and the small dust fraction were deduced from the infrared…
We present the first detailed analysis of three extragalactic fields (IRAC Dark Field, ELAIS-N1, ADF-S) observed by the infrared satellite, AKARI, using an optimised data analysis toolkit specifically for the processing of extragalactic point sources. The InfraRed Camera (IRC) on AKARI complements the Spitzer space telescope via its comprehensive coverage between 8-24 microns filling the gap between the Spitzer IRAC and MIPS instruments. Source counts in the AKARI bands at 3.2, 4.1, 7, 11, 15 and 18 microns are presented. At near-infrared wavelengths, our source counts are consistent with coun…
We use two 4.5micron Spitzer (IRAC) maps of the NGC 1333 region taken over approx. 7 yr interval to determine proper motions of its associated outflows. This is a first, successful attempt at obtaining proper motions of stellars outflow from Spitzer observations. For the outflow formed by the Herbig-Haro objects HH7, 8 and 10, we find proper motions of approx. 9-13 km/s, which are consistent with previously determined optical proper motions of these objects. We determine proper motions for a total of 8 outflows, ranging from approx. 10 to 100 km/s. The derived proper motions show that out of t…
The Spitzer-Cosmic Assembly Deep Near-Infrared Extragalactic Legacy Survey (S-CANDELS; PI G. Fazio) is a Cycle 8 Exploration Program designed to detect galaxies at very high redshifts (z > 5). To mitigate the effects of cosmic variance and also to take advantage of deep coextensive coverage in multiple bands by the Hubble Space Telescope Multi-Cycle Treasury Program CANDELS, S-CANDELS was carried out within five widely separated extragalactic fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the HST Deep Field North, and the Extended Groth Strip. S-CANDELS bu…
In recent years the wavelength dependence of interstellar extinction from the ultraviolet (UV), optical, through the near- and mid-infrared (IR) has been studied extensively. Although it is well established that the UV/optical extinction law varies significantly among the different lines of sight, it is not clear how the IR extinction varies among various environments. In this work, using the color-excess method and taking red giants as the extinction tracer, we determine the interstellar extinction Alambda in the four Spitzer/IRAC bands of the Coalsack nebula, a nearby starless dark cloud, ba…
Context. The largest grains (0.5-1 micron) in the interstellar size distribution are efficient in scattering near- and mid-infrared radiation. These wavelengths are therefore particularly well suited to probe the still uncertain high-end of the size distribution. Aims. We investigate the change in appearance of a typical low-mass molecular core from the Ks (2.2 micron) band to the Spitzer IRAC 3.6 and 8 micron bands, and compare with model calculations, which include variations of the grain size distribution. Methods. We combine Spitzer IRAC and ground-based near-infrared observations to chara…
We present {\it Spitzer} IRAC mid-infrared photometry on the massive star forming region AFGL 437 (IRAS 03035+5819). From the IRAC colour-colour diagram, we identify several new embedded YSOs within 64 arcsec of the central compact cluster. Using the IRAC ratio images, we investigate the molecular outflows associated with the highly embedded young stellar object WK34 in the central cluster. We attribute the lobes seen (extended to $\sim$ 0.16 pc in the north) in the ratio map to shocked molecular hydrogen emission. IRAC images reveal a large diffuse nebulosity associated with the central clust…
We present observations from the First Light Infrared TEst CAMera (FLITECAM) on board the Stratospheric Observatory for Infrared Astronomy (SOFIA), the Spitzer Infrared Array Camera (IRAC) and the Spitzer Infrared Spectrograph (IRS) SH mode in three well-known Photodissocation Regions (PDRs), the reflection nebulae (RNe) NGC 7023 and NGC 2023 and to the southeast of the Orion Bar, which are well suited to probe emission from Polycyclic Aromatic Hydrocarbon molecules (PAHs). We investigate the spatial behaviour of the FLITECAM 3.3 um filter as a proxy for the 3.3 um PAH band, the integrated 11.…
The mid-far-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 micron sample are presented. The data were collected using all three instruments, IRAC, IRS, and MIPS, aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20 arcsec diameter circular apertures. The MIPS data were obtained in SED mode, providing very low resolution spectroscopy (R ~ 20) between ~ 55 and 90 microns in a larger, 20 by 30 arcsec synthetic a…
Based on the photometric data from the Spitzer/SAGE survey and with red giants as the extinction tracers, the mid-infrared (MIR) extinction laws in the Large Magellanic Cloud (LMC) are derived for the first time in the form of A_λ/A_Ks, the extinction in the four IRAC bands (i.e., [3.6], [4.5], [5.8] and [8.0]um) relative to the 2MASS Ks band at 2.16um. We obtain the near-infrared (NIR) extinction coefficient to be E(J-H)/E(H-Ks)=1.29\pm0.04 and E(J-Ks)/E(H-Ks)=1.94\pm0.04. The wavelength dependence of the MIR extinction A_λ/A_Ks in the LMC varies from one sightline to another. The overall mea…
Spitzer Space Telescope InfraRed Array Camera (IRAC) images of M100 show numerous long filaments with regularly-spaced clumps, suggesting the associated cloud complexes formed by large-scale gravitational instabilities in shocked and accumulated gas. Optical images give no hint of this underlying regularity. The typical spacing between near infrared (NIR) clumps is ~410 pc, which is ~3 times the clump diameter, consistent with the fastest growing mode in a filament of critical line density. The IRAC magnitudes and colors of several hundred clumps are measured in the most obvious 27 filaments a…
The study of outer halo globular cluster (GC) populations can give insight into galaxy merging, globular cluster accretion and the origin of GCs. We use archival Subaru Hyper Suprime-Cam (HSC) data in concert with space-based GALEX, IRAC and Gaia EDR3 data to select candidate Globular clusters (GCs) in the outer halo of the M81 group for confirmation and future study. We use a small sample of previously-discovered GCs to tune our selection criteria, finding that bright already-known GCs in the M81 group have sizes that are typically slightly larger than the Subaru PSF in our fields. In the opt…
We present ~120,000 Spitzer/IRAC candidate young stellar objects (YSOs) based on surveys of the Galactic midplane between l~255 deg and 110 deg, including the GLIMPSE I, II, and 3D, Vela-Carina, Cygnus X, and SMOG surveys (613 square degrees), augmented by near-infrared catalogs. We employed a classification scheme that uses the flexibility of a tailored statistical learning method and curated YSO datasets to take full advantage of IRAC's spatial resolution and sensitivity in the mid-infrared ~3-9 micron range. Multi-wavelength color/magnitude distributions provide intuition about how the clas…
We examine the UV reprocessing efficiencies of warm dust and polycyclic aromatic hydrocarbons (PAHs) through an analysis of the mid- and far-infrared surface luminosity densities of 85 nearby H$α$-selected star-forming galaxies detected by the volume-limited KPNO International Spectroscopic Survey (KISS). Because H$α$ selection is not biased toward continuum-bright objects, the KISS sample spans a wide range in stellar masses ($10^8$-$10^{12}\rm{M}_\odot$), as well as H$α$ luminosity ($10^{39}$-$10^{43}\rm{ergs/s}$), mid-infrared 8.0$μ$m luminosity ($10^{41}$-$10^{44}\rm{ergs/s}$), and [Bw-R] …
We present the Spitzer Data Fusion, a database incorporating far-ultraviolet to far-infrared flux measurements as well as photometric and spectroscopic redshifts for 4.4 million IRAC-selected sources detected over 8 extragalactic fields covering 65 deg$^2$ observed by Spitzer in all IRAC and MIPS bands during its cryogenic mission. Deeper Spitzer observations carried out during its warm mission over 5 sub-fields as part of the SERVS project are also presented and analysed in a similar fashion, detecting 2.8 million IRAC-selected sources over 18 deg$^2$ and merging them with multi-wavelength ca…
We present $Spitzer$ IRAC mid-infrared point source catalogs for mosaics covering the fields of the nearby ($\lesssim$4 Mpc) galaxies NGC 55, NGC 253, NGC 2366, NGC 4214, and NGC 5253. We detect a total of 20159 sources in these five fields. Point spread function photometry was performed on sources detected in both $Spitzer$ IRAC 3.6 $μ$m and 4.5 $μ$m bands at greater than 3$σ$ above background. These data were then supplemented by aperture photometry in the IRAC 5.8 $μ$m and 8.0 $μ$m bands conducted at the positions of the shorter wavelength sources. For sources with no detected object in the…
We present a comprehensive infrared study of supernova remnants (SNRs) in the Large Magellanic Cloud (LMC) using near- to mid-infrared images taken by Infrared Array Camera (IRAC; 3.6, 4.5, 5.8, and 8 μm) and Multiband Imaging Photometer (MIPS; 24 and 70 μm) onboard the Spitzer Space Telescope. Among the 47 bona fide LMC SNRs, 29 were detected in infrared, giving a high detection rate of 62%. All 29 SNRs show emission at 24 μm, and 20 out of 29 show emission in one or several IRAC bands. We present their 4.5, 8, 24, and 70 μm images and a table summarizing their Spitzer fluxes. We find that th…
Spitzer's final Infrared Array Camera (IRAC) observations of SN 1987A show the 3.6 and 4.5 $μ$m emission from the equatorial ring (ER) continues a period of steady decline. Deconvolution of the images reveals that the emission is dominated by the ring, not the ejecta, and is brightest on the west side. Decomposition of the marginally resolved emission also confirms this, and shows that the west side of the ER has been brightening relative to the other portions of the ER. The infrared (IR) morphological changes resemble those seen in both the soft X-ray emission and the optical emission. The in…
We have conducted a study of star formation in the outer Galaxy from 65\degr$< l <$265\degr~in the region observed by the GLIMPSE360 program. This {\it Spitzer} warm mission program mapped the plane of the outer Milky Way with IRAC at 3.6 and 4.5~$μ$m. We combine the IRAC, {\it WISE}, and 2MASS catalogs and our previous results from another outer Galaxy survey and identify a total of 47,338 Young Stellar Objects (YSOs) across the field spanning $>$180\degr\ in Galactic longitude. Using the $DBSCAN$ method on the combined catalog, we identify 618 clusters or aggregations of YSOs having 5 or mor…
We present SED modeling of a sample of 34 K-selected galaxies at z ~ 2.3. These galaxies have NIR spectroscopy that samples the rest-frame Balmer/4000A break as well as deep photometry in thirteen broadband filters. New to our analysis is IRAC data that extend the SEDs into the rest-frame NIR. Comparing parameters determined from SED fits with and without the IRAC data we find that the IRAC photometry significantly improves the confidence intervals of Tau, A_v, stellar mass, and SFR for individual galaxies, but does not systematically alter the mean parameters of the sample. We use the IRAC da…
Based on the data obtained from the Spitzer/GLIPMSE Legacy Program and the 2MASS project, we derive the extinction in the four IRAC bands, [3.6], [4.5], [5.8] and [8.0] micron, relative to the 2MASS Ks band (at 2.16 micron) for 131 GLIPMSE fields along the Galactic plane within |l|<65 deg, using red giants and red clump giants as tracers. As a whole, the mean extinction in the IRAC bands (normalized to the 2MASS Ks band), A_[3.6]/A_Ks=0.63, A_[4.5]/A_Ks=0.57, A_[5.8]/A_Ks=0.49, A_[8.0]/A_Ks=0.55, exhibits little variation with wavelength (i.e. the extinction is somewhat flat or gray). This is …
This paper presents a study of the rate and efficiency of star formation in the NGC 6334 star forming region. We obtained observations at J, H, and Ks taken with the NOAO Extremely Wide-Field Infrared Imager (NEWFIRM) and combined them with observations taken with the Infrared Array Camera (IRAC) camera on the Spitzer Space Telescope at wavelengths λ = 3.6, 4.5, 5.8, and 8.0 μm. We also analyzed previous observations taken at 24 μm using the Spitzer MIPS camera as part of the MIPSGAL survey. We have produced a point source catalog with >700,000 entries. We have identified 2283 YSO candidates, …
Aims: We aim at measuring mass-loss rates and the luminosities of a statistically large sample of Galactic bulge stars at several galactocentric radii. The sensitivity of previous infrared surveys of the bulge has been rather limited, thus fundamental questions for late stellar evolution, such as the stage at which substantial mass-loss begins on the red giant branch and its dependence on fundamental stellar properties, remain unanswered. We aim at providing evidence and answers to these questions. Methods: To this end, we observed seven 15 times 15 arcmin^2 fields in the nuclear bulge and its…
